Mount Prospect, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

112
FXUS63 KLOT 032342
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
542 PM CST Tue Mar 3 2026

.KEY MESSAGES...

- Warmer and occasionally wet weather is in store from the mid
  to late week period onward. Confidence is higher in more
  widespread rain late Wednesday night into Thursday and again
  late Friday into early Saturday.

&&

.DISCUSSION...
Issued at 142 PM CST Tue Mar 3 2026

Through Thursday Night...

It`s a gray early March day out there today with low-hanging
overcast residing atop the area. The cloud cover has kept
conditions cooler out there than yesterday with temperatures
early this afternoon sitting in the upper 30s and lower 40s.
Meanwhile, a sharp baroclinic zone is draped across south-
central IL with an impressive density gradient on either side; a
stretch of only about 50 miles presently separates mid 40s
temps from mid 60s. A series of subtle impulses transversing the
baroclinic zone is driving waves of showers across central IL.
Most coverage since early this morning has stayed south of the
CWA, but a few lighter showers have found their way across our
south.

The remainder of today will be pretty steady state with the
occasional light shower possible south of US Rt. 24 into this
evening. There`s a signal from a handful of camps for rain
coverage to expand across central IL as another vort lobe scoots
across and possibly targets our southern tier of counties for
steadier rainfall late this evening through much of the night.
The rest of the area will be staying dry tonight and we`ll
probably even see some clearing across maybe the northern half
of the CWA. Areas that do see clearing, particularly those west
of the Fox Valley, may see some fog develop overnight into
Wednesday. With stronger flow residing just off the surface and
mixed signals from model guidance, opted to leave any explicit
fog mention out of the forecast for tonight.

Shower coverage is expected to continue prioritizing areas
south of the CWA into Wednesday. It wouldn`t be surprising to
see the whole area rain-free throughout the morning and maybe
much of the afternoon as well. Early in the day, a surface low
will begin to lift northeast into the region across MO and
eventually into central and northern IL by Wednesday night. That
baroclinic zone, acting as the cyclone`s warm front, will
propagate northward during the day and rain coverage will follow
suit. Scattered showers may move over our southern and
southwestern CWA as early as the afternoon, but some of the
latest high-res guidance suggest we may not see much precip
expand into the area until the evening. Densely scattered to
widespread showers are then expected around most of the area
through the night and into Thursday.

With guidance coming into better agreement on the surface
reflection passing directly overhead, there is a growing signal
for western and northwestern portions of our CWA to see
generally lesser rain coverage on the northwest side of the low
track during this period than areas farther south and east. As
many as several hundred Joules of elevated CAPE will lift into
northern IL Wednesday night into Thursday. Ambient forcing
should be sufficient with steep lapse rates atop the stable
layer to provide a decent shot at some elevated convection. The
event should wrap it up in the form of scattered lighter showers
late Thursday morning into afternoon as the low pulls away to
the east. Thursday night will be quiet before our next
opportunity for rain arrives early Friday.

The low tracking overhead will also provide us with a good
setup for widespread fog tomorrow night. Visibilities are
expected to drop from south to north as the warm front
approaches during the evening. There is a signal that dense fog
could be possible in our south early enough to impact portions
of the evening commute. Chances will only build and expand
northward moving into the late evening and overnight. The fog
may also attempt to linger well into the morning which could
potentially mean hazardous travel around the Chicago metro for
the Thursday morning commute. With strong support from guidance,
decided to add fog area-wide to the forecast for Wednesday
evening into Thursday morning.

Doom

Friday through Tuesday...

On Friday, mid-level southwesterly flow will strengthen as a mid-
level jet ejects northeast across the Plains into the Upper
Midwest. This will send a low amplitude mid-level shortwave racing
northeastward into the Upper Midwest sometime late Friday morning
into early Friday afternoon, though there is variance in the
guidance regarding the track and strength of this feature.
Scattered showers and thunderstorms accompanying this feature may
impact parts of the region for a period into Friday afternoon.
However, it still appears there will be a good amount of dry time
during the day (more than implied by the currently high gridded
PoPs).

Temperatures on Friday are expected to soar well into the 60s
into the low 70s (near record territory for ORD and RFD which is
70 at both sites on Friday) for most through the afternoon as a
surface warm front surges northward across Illinois and Indiana.
However, as is typical this time of year, onshore flow ahead of
this front across far northeastern IL (including parts of Chicago)
may keep conditions much cooler through much of the day until the
warm front clears this area. The combination of these very warm
temperatures and unseasonably high dew points, into the upper 50s
to near 60, will support an unstable and strongly sheared warm
sector supportive of a conditional threat of severe thunderstorms
Friday afternoon. The main question at this point is if any of
these early afternoon storms will be able to become surface based
near the quickly approaching warm front before the main focus for
them shifts to our northeast later in the day. If they do become
surface based, then severe storms would be more of threat for a
period Friday afternoon, particularly near the surface boundary.
However, at this time confidence on severe threat with these
storms is low at this time. Ultimately, it is going to come down
to the timing of the northward frontal surge into northern IL
Friday afternoon.

A period of storm free weather could set up for a period late
Friday afternoon and evening following this initial impulse,
though south-southwesterly winds do look to become gusty (35+
mph) for a period. Expect shower and thunderstorm chances and
coverage to ramp-up again late Friday night into early Saturday
morning in association with a cold front sweeping eastward across
the area. The currently unfavorable diurnal timing of the cold
front passage does raise questions as to the threat for organized
severe weather with this activity locally. However, the combined
presence of near record warm temperatures and dew points Friday
night with a strongly sheared kinematic environment certainly will
support at least a conditional risk for some stronger storms
capable of damaging winds late Friday night.

Rain chances will come to an end following the cold frontal
passage on Saturday, at least for a few days. Temperatures will
cool down a bit immediately behind the front Saturday PM, but
generally remain well above average through early next workweek.
For areas that don`t receive much rain in the upcoming stretch,
we`ll need to monitor for elevated fire danger on Sunday due to
mild temps paired with fairly low dew points and gusty southwest
winds. Current medium to long-range ensembles point towards a
stronger cold front passage in the wake of a possible formidable
mid-latitude cyclone with potentially widespread precipitation mid
next week, bringing a return to colder conditions by later in the
week/mid-March.

KJB/Castro

&&

.AVIATION /00Z TAFS THROUGH 06Z THURSDAY/...
Issued at 542 PM CST Tue Mar 3 2026

There are several aviation weather concerns through the next 30
hours:

- Potential for low-MVFR/IFR and possibly briefly LIFR cigs and
  vsbys tonight into Wednesday morning.

- Showers and drizzle expected to develop late Wednesday
  afternoon and into Wednesday night.

- Rapdily-deteriorating flying conditions Wednesday evening with
  widespread IFR to LIFR conditions expected Wednesday night.

Lingering pockets of MVFR cigs near the lake should generally
erode early this evening. Thereafter, a moist airmass in place
combined with some clearing north of I-80 will support the
development of BR and low cloud cover. Uncertainty exists in how
things will evolve tonight, particularly related to any vsby
restrictions due to increasing flow off 500-1000 feet off the
surface late tonight. Based on the latest available guidance,
trended cigs/vsbys down tonight, but not all the way to the
most pessimistic guidance.

Conditions will briefly improve towards midday Wednesday, but
cigs will then trend down quickly through the afternoon and
evening. A period of showers and/or drizzle will likely
accompany the lowering cigs late in the afternoon and evening.
Towards the tail end of the ORD/MDW extended TAFs, the signal is
high for the development of LIFR conditions due to expansive low
stratus and fog which will probably persist well into Thursday.

Carlaw

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.

&&

$$

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